Xu Collection, Upper Volume Radical: Metal (jīn) Page 1307, Entry 02 Pronounced yù. Pronounced yù. Explanations from the Explanation of Simple and Compound Characters (Shuowen Jiezi) state it is a tool used for hooking tripods and charcoal. The character structure includes the Metal radical and the phonetic component gu. The Broad Rhymes (Guangyun) describes it as a charcoal hook. Another explanation in the Explanation of Simple and Compound Characters (Shuowen Jiezi) defines it as copper filings. The Treatise on Food and Money in the History of the Former Han (Qianhan Shihuozhi) records that unscrupulous people would surreptitiously scrape the surface of coins to obtain copper filings (yu). Note: Chen Zan explains that yu refers to copper filings. By scraping the coin surface, one obtains shavings which are then used to cast new coins. Shigu says the pronunciation of yu is the same as that for bathing. A reference in the Discussion on Coin Casting by Kong Ji of the Southern Song mentions the five-zhu coin, noting that outlines were cast on the edges and surfaces of the coins to prevent them from being scraped to obtain copper filings (yu). The Five Sounds Register (Wuyinpu) states that the gradual wearing away of an object through scraping is called yu. The modern common term for grinding an object until it is smooth is derived from this. Pronounced róng. In the term gouyu, it refers to a tool used for retrieving charcoal.